Microphones used for portable electronic devices may be “directional” or “omni-directional.” Such devices (e.g., cellular telephones) may, at times, be used in circumstances in which the microphone is subject to transient (e.g., “popping” of a spoken “p” phoneme) or sustained (e.g., wind) airflow disturbance. In certain conditions, airflow incident upon the microphone may be so substantial as to be picked up by the microphone and produce an undesirable noise signal that interferes with the microphone's use. During a phone call, for instance, audible airflow noise may make sound transmissions difficult to hear on the part of a listener.
Typically, several types of omni-directional microphones have been used in portable electronic communication devices, such as cellular phones or cell phone accessories. Although omni-directional microphones are considered to be less sensitive to wind-noise from air blowing into microphone compared to directional microphones, wind-noise often remains problematic. Thus, noise-cancelling algorithms are sometimes used to combat the problem and improve acoustical performance. However, such electronic solutions requiring power consumption are not always suitable in portable devices powered by limited battery capacity. Furthermore, it is often the case that the device in which wind-noise is to be reduced has no power supply at all.
Windscreen barriers are of particular interest for use in directional microphones. The benefit of directional microphones is that the sound picked up may be of better quality, while a limitation is that directional microphones are much more sensitive to wind-noise than omni-directional microphones.
The use of wind-noise barriers in directional microphones has been investigated. Windscreen barriers are typically provided in the form of porous membranes. Examples of such barriers are, for instance, described in U.S. Pat. Nos. 4,966,252; 5,442,713; and 2,536,261.
Such barriers are likely to be of interest for being provided in accessories, like portable hands-free devices in relation to cellular phones, for instance, in headsets, and the like. One such headset with a windscreen barrier is described in WO 2005/067653, in which a microphone is placed in an air-filled chamber surrounded by a windscreen barrier made of a mesh material.
The above-described barriers attempt to provide some degree of wind-noise reduction. However, the barriers have limited noise reduction effectiveness with respect to design (e.g., size, dimensions, etc.) limitations and/or compromised sound reception/transmission quality.